1. Field of the Invention
This invention relates to information networks and methods of operation. More particularly, the invention relates to a system and method for controlled access to shared-medium public and semi-public IP networks.
2. Description of the Prior Art
With the vast increase of private, semi-public and public shared-medium IP networks, a growing problem for network and service administrators is how to control and restrict access to the networks only to authorized and registered devices and users. One example of the problem relates to corporate IP network administrators who deal with an increasingly mobile work force that have deployed IP network access ports (typically IEEE 802.X or similar medium) throughout their corporate facilities for shared use by their corporate employees. Such shared network access ports work in conjunction with Dynamic Host Control Protocol (DHCP) servers to dynamically assign the appropriate IP address and other parameters to a mobile employee""s device. A strong concern in the use of such networks is preventing visitors or unauthorized persons from taking advantage of the exposed network access ports to gain IP connectivity to the internal corporate network (intranet).
Another example relates to Internet Service Providers (ISPs) offering public services over shared-medium, such as the increasingly popular cable-modem technology, which in many cases simulates IEEE 802.X medium access over cable TV plants. The distribution medium (cable TV plant) is shared among thousands of homes (users), of which only a subset is paying for internet access using cable modems. The DHCP protocol is also typically used as a means to assign an IP address and other parameters to the cable-modem user attempting to gain network services. In such case, the ISP has a strong interest to prevent unauthorized (non-paying) users from using the IP/internet services by obtaining a usable address for a particular cable plant segment, which is easily accomplished.
Variations of the previous examples also exist using a variety of wire line and wireless access technology and access devices (personal computers, smart internet phones) for internet and intranet services to users sharing a common network medium.
Prior art related to such examples includes:
U.S. Pat. No. 5,732,137 entitled xe2x80x9cMethod and Apparatus for Secure Remote Authentication in a Pubic Networkxe2x80x9d, issued Mar. 24, 1998, discloses a method and apparatus for user authentication in a network environment between a client computer (workstation) and a remote destination server coupled to a network. A user operating the client workstation provides a log-in address as anonymous file transfer protocol and a password as the user""s e-mail address. The destination server compares the user""s e-mail address provided as a password to a list of authorized user addresses. If the user e-mail address provided is not on the destination service list of authorized users"" addresses, then the user logon request is automatically denied. If the user""s e-mail address is located on the list of authorized user""s addresses maintained by the destination server, the destination server generates a random number (X) and encrypts the random number in an ASCII representation using encryption techniques provided by the Internet Privacy-Enhanced Mail (PEM). The encrypted random number is stored in the file as the user""s anonymous directory. The server further establishes the encrypted random number as a one-time password for the user. The client workstation initiates a file transfer request to obtain the encrypted PEM random number as a file transfer from the destination server. The destination server then sends the PEM encrypted password""s random number as the file transfer file over the internet to the client workstation. The client workstation decrypts the PEM encrypted file utilizing the user""s private RSA key in accordance with established PEM decryption techniques. The client workstation then provides the destination server with the decrypted random number password which is sent in the clear over the internet to log-in to the destination server. Upon receipt of the decrypted random number password, the destination server permits the user to log-in to the anonymous directory thereby completing the user""s authentication procedure and accomplishing log-in.
U.S. Pat. No. 5,757,924 entitled xe2x80x9cNetwork Security Device Which Performs MAC Address Translation Without Affecting the IP Address,xe2x80x9d issued Mar. 26, 1998 discloses a network security device connected between a protected client and a network. The network security device negotiates a session key with any other protected client. The security device is self-configuring and locks itself to the IP address of the client. Thus, the client cannot change its IP address once set and, therefore, cannot emulate the IP address of another client. When a packet is transferred in from the protected host, the security device translates the MAC address of the client to its own MAC address before transmitting the packet into the network. Packets addressed to the host contain the MAC address of the security device. The security device translates its MAC address to the client""s MAC address before transmitting the packet to the client.
U.S. Pat. No. 5,774,652 entitled xe2x80x9cRestricted Access Computer System,xe2x80x9d issued Jun. 30, 1998 discloses a general purpose computing platform in a controlled system including a control hardware device and a control software program. The control hardware device is connected to the computing platform into an access-status device such as a coin hopper or the like. The control software program runs on the computing platform and, in a secure mode, replaces the graphical user interface portion of the operating system of the general purpose computing platform. The control hardware device control software program interoperates to allow access to application software programs on the computing program platform only when certain conditions are satisfied. The control hardware device resets the computing platform if the control software program fails to communicate therewith. The control hardware device also restricts operation of the user keyboard therewith. The control hardware device also restricts operation of the user keyboard and display monitor to reduce the possibility of unauthorized use to the computer system.
The prior art for controlled access to networks is implemented in a combination of dedicated hardware control servers and specialized software. Moreover, the prior art requires extensive modifications to end systems or requires specialized and dedicated hardware to be inserted in front of every network client device. Such systems rely on encryption and sophisticated key management system which makes such techniques expensive, inflexible, and not suitable for shared-medium public and semi-public IP networks.
What is needed is a system and method that is applicable to existing and future network access infrastructures which works in conjunction with popular and established IP protocols and communication layer network equipment without requiring any modifications to currently used internet protocols.
An object of the invention is a system and method which makes it impossible or very difficult for unauthorized devices and users to obtain IP network services on shared-medium public and semi-public networks.
Another object is a system and method for controlling access to shared-medium public and semi-public networks using standard network protocols and communication layers without modification.
Another object is a system and method for preventing unauthorized devices and users from obtaining network services in a dynamic user address environment.
These and other objects, features and advantages are achieved in a system comprising communication layers (OSI 2 and 3) and work equipment (routers and/or switches) which work in conjunction with Dynamic Host Control Protocols (DHCP) and Address Resolution Protocols (ARP). Routers and/or switches are configured to disable ARP and IP addresses to MAC addresses on outbound interfaces to network access points. The IP routers and/or switches are configured to accept and forward DHCP requests from user devices to one or more DHCP servers that have access to user and device registration data. In operation at configuration time, authorized users and their authorized devices register for service by providing the DHCP server with user identification for log-in, passwords, MAC addresses, etc. The information is validated and entered into a server database for future authentication queries. When users connect to the network access point, a DHCP exchange is initiated to obtain a valid IP address and other associated parameters. The DHCP client initiates a MAC broadcast for IP addresses which contain in the request, the end user""s device MAC address. The associated router/switch picks up and forwards to a DHCP server, the end user""s device request. The DHCP server will process the end user""s request and extract the end user""s device MAC address. With the end user""s MAC address, the DHCP server accesses its device, and/or user information in the data base. If the MAC address is not registered, the DHCP server refuses to handle the request, logs the attempt, potentially alerting network operators of a security breach. If the MAC address is registered, the DHCP server selects an appropriate IP address and associated parameters to be returned to the requesting end user and connects via programming or commands interface to the router switch that is forwarding the DHCP request on behalf of the end user device. The server adds the ARP IP to the MAC address table entry with the selected IP address and end user""s MAC address. The end user device authentication and IP lease are optionally marked as provisional and a timer is started for a suggested duration. Optionally, the DHCP server dynamically sets up filter rules in the router switch limiting access to a subset of IP addresses such as the address of a log-in server. DHCP processing is completed and an IP address is assigned to the requesting end user""s device by DHCP. For enhanced security, end users are optionally instructed to access and authenticate themselves through a log-in server within 60 seconds, after obtaining IP connectivity with DHCP. When the end user successfully authenticates the log-in server, the end user can be moved and the DHCP server changes from provisional to full access. When the timer expires, if the DHCP server finds the authenticating user""s state is provisional, the server will revoke the IP lease, invalidate the corresponding ARP to MAC table entry in the associated router/switch, and reset any IP permissive filtering for that device. If the DHCP server finds the user in the full authenticated state, the server will simply remove the restrictive filters so the user can enjoy the full range of authorized IP services.